This invention relates generally to pivot joints, and in particular to a pivot joint useful for connecting a headlamp adjustor to a reflector inside a headlamp assembly or an external reflector and lens headlamp assembly. The improved socket assembly can be used effectively with many types of ball studs, including disengageable ball studs or conventional spherical, semi-spherical or “eared” ball studs.
Pivotable spherical joints, commonly referred to as ball joints, include a ball stud engaged in a socket. Such joints have a wide variety of applications where a pivotable connection between two parts is desirable. For example, they may be used in many types of linear actuators and have been found to be particularly useful in automotive lamp assemblies. As seen in U.S. Pat. No. 5,707,133, automotive lamp assemblies used as headlights typically comprise several basic parts: a support frame, a reflector, a lens, a bulb, and one or more adjusters.
In the automotive lamp assembly example, the support frame houses the reflector and the bulb on a pivotable mounting to allow the aim of the light to be adjusted using the adjuster. The lens seals the front of the assembly to protect it from the elements assailing the front end of the vehicle and provides an aerodynamic shape and attractive appearance. The reflector mounts inside the housing on one fixed ball joint and is adjustable horizontally and vertically using adjusters that interface with the reflector through moving ball joints. The moving ball joints are moveable by actuating the adjusters connected to the moving ball joints by a ball stud having a head and a shaft. Another type of automotive headlamp assembly that uses linear actuators is shown in U.S. Pat. No. 5,360,282. In this type of headlamp assembly the linear actuator is mounted to a bracket and the ball joint end supports a reflector, lens and light bulbs. This type of application requires a higher strength ball joint due to the additional weight being supported. In particular, pull-out strength of the ball joint needs to be greater to withstand vibration. A socket design such as those in U.S. Pat. Nos. 6,692,176 and 6,758,622 provide improved socket designs to resist accidental pull-out of the ball stud.
While one possible application of the present invention is in headlamp assemblies, other applications are possible and references to use in a headlamp assembly should not be deemed to limit the application of the present invention. Conventional ball joints for use in automotive lamp assemblies typically include a ball stud with a spherical engagement head extending from an adjuster. The ball stud is moveable linearly in and out of the adjuster. Examples of such ball studs and corresponding sockets are shown in U.S. Pat. Nos. 4,689,725; 5,673,992; 5,095,411; and 5,186,532. Additionally, while the improved ball socket design described herein may be used with ball studs having “ears” or engaging tabs or semi-spherical ball stud designs (such as those disclosed in U.S. Pat. Nos. 4,689,725 and 5,186,531), a disengageable ball stud (such as those disclosed in U.S. Pat. Nos. 6,113,301 and 6,247,868), can also be used advantageously with the present invention.
As is known in the art, ball studs interface with a socket, typically plastic, such as the one shown in U.S. Pat. No. 6,837,716. Generally, the sockets are attached to the reflector such that movement of the ball stud effectuates movement of the reflector. For example, the socket is attached to a boss with a fastener, the boss having an aperture therein for receiving the fastener. Conventional sockets are secured to the reflector of the headlamp by either screwing the socket into the reflector by placing a screw through a screw hole in the reflector, like that in U.S. Pat. No. 6,247,868, or can be pushed into a through hole in the reflector and secured using tabs or panels which spring outward and “snap-fit” into the reflector hole, like that shown in U.S. Pat. No. 6,837,716. Another conventional socket like that shown in U.S. Pat. No. 6,231,223 is pushed into a blind hole and uses deformable fins to hold the socket inside by friction.
Several problems exist with installation of conventional sockets. For those requiring that the socket be screwed in, an additional assembly task is required by the manufacturer to place the screw into the socket, and during assembly of the headlamp, each socket must be individually screwed into each reflector. This requires extra time and cost in both manufacturing and installation. Conventional snap-in sockets also have a disadvantage in that a through hole is required for the snap fit fingers to work. Snap fit designs do not work in blind holes since a ledge inside the hole is needed for the snap feature. However, blind holes are often preferred over through holes for ease of manufacturing and tool design and maintenance. Through holes require the reflector molding tool to have a parting line surface within the through hole and often require the use of tool side action as well in order to mold the reflector. This adds complexity and cost to the tool design and construction. Also, added tool maintenance and quality control expense of the parting line surface is needed to prevent flash. Prior socket designs that are pushed into blind holes either have inadequate retention to prevent accidental pull out or require a very high force to install into the hole.
Accordingly, the need exists for a socket which can be inserted into a blind hole. A need also exists for a socket which can be inserted into a reflector fairly easily by hand without the extra force of a tool. A need also exists for a socket that resists accidental pull-out from the reflector. It is also desirable that such a socket be easily and cost-effectively manufactured and installed, and also that it can be used with any number of different types of ball studs.